sfc /scannow

Steps

1. Save work, connect reliable power, and open Windows Terminal or Command Prompt as administrator.
2. If following Microsoft system-file repair guidance, complete DISM /Online /Cleanup-Image /RestoreHealth first, then run sfc /scannow.
3. Allow Verification to reach 100%, read the exact final SFC message, restart if appropriate, and retest the original Windows symptom.

Expected result

SFC reports whether Windows Resource Protection found no integrity violations, found and repaired corrupt files, found corrupt files but could not repair some of them, or could not perform the requested operation. Interpret that result before choosing the next step.

What sfc /scannow does

System File Checker checks protected Windows system files. Microsoft documents /scannow as scanning the integrity of all protected system files and repairing files with problems when possible.

SFC is different from DISM. DISM services and repairs the Windows image or component store, while SFC checks protected Windows system files. Microsoft current support guidance for corrupted system files runs DISM first and SFC afterward.

How to run SFC /scannow safely

Use SFC when the symptoms justify a protected-system-file check rather than as an automatic response to every Windows problem. Keep the computer powered and let verification complete before interpreting the result.

sfc /scannow

1. Open Windows Terminal or Command Prompt as administrator.
2. Run sfc /scannow.
3. Do not close the window until Verification reaches 100%.
4. Read and preserve the complete Windows Resource Protection result.
5. Restart if appropriate, then reproduce the original symptom.

Note: A completed command is not the same as a repaired problem. The final Windows Resource Protection message determines what SFC found.

Understand the four main SFC results

Microsoft support documentation describes four common outcomes after sfc /scannow. Each one leads to a different troubleshooting decision.

1. Windows Resource Protection did not find any integrity violations — SFC did not identify missing or corrupted protected system files.
2. Windows Resource Protection could not perform the requested operation — the scan did not complete normally; Microsoft guidance includes running SFC in Safe Mode.
3. Windows Resource Protection found corrupt files and successfully repaired them — SFC repaired protected files and details are recorded in CBS.log.
4. Windows Resource Protection found corrupt files but was unable to fix some of them — preserve the details and investigate the unrepaired files rather than treating the run as successful.

Note: Record the exact final wording. A successful repair result is materially different from a result saying some files could not be fixed.

Should you run DISM before SFC?

For Microsoft’s support procedure used to repair missing or corrupted Windows system files, run DISM /Online /Cleanup-Image /RestoreHealth first. DISM can repair the component-store source used when SFC needs replacement files.

After DISM reports that the operation completed successfully, run sfc /scannow and interpret its result. This creates a clearer sequence: repair the Windows image first, then check protected system files.

DISM /Online /Cleanup-Image /RestoreHealth

Note: Do not repeatedly alternate DISM and SFC without reading their results. Preserve any error before deciding the next repair.

If SFC found corrupt files and repaired them

A successful repair means SFC found protected system-file corruption and was able to repair it. Restart when appropriate, then repeat the exact Windows task that originally failed.

If the original symptom remains after a successful SFC repair, do not assume more SFC runs will solve it. The remaining cause may be an application, driver, account, service, configuration, update, or hardware path.

If SFC cannot repair some files

Microsoft records SFC repair information in the CBS log. You can extract SFC-related entries from CBS.log to a smaller text file using findstr, which helps identify what SFC reported instead of guessing from the summary alone.

If DISM has not already been run as part of the current repair procedure, follow the appropriate DISM guidance and run SFC again after the component-store repair succeeds. Preserve any unrepaired-file details before considering broader recovery actions.

findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log > "%userprofile%\Desktop\sfcdetails.txt"

Warning: Do not manually replace protected Windows files merely because a filename appears in CBS.log. Confirm the specific failure and use an appropriate repair or recovery procedure.

Use sfc /verifyonly when you do not want repairs

Microsoft documents /verifyonly as scanning the integrity of protected system files without performing repair operations. It is useful when the immediate goal is verification rather than modification.

If /verifyonly reports an integrity problem, decide on the repair path deliberately instead of assuming the verification command fixed anything.

sfc /verifyonly

Note: /verifyonly verifies protected files but does not perform repairs.

Offline SFC is a separate recovery scenario

SFC also supports offline repair parameters including /offbootdir and /offwindir. These require the correct boot and Windows directory paths for the offline installation.

Do not copy example drive letters blindly in Windows Recovery Environment because the Windows partition can have a different letter there. Identify the actual offline Windows installation first.

sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows

Note: The C: paths are examples only. Use the actual boot and Windows directories for the offline installation.

Verify Windows after SFC finishes

The useful endpoint is not simply that SFC reached 100%. Retest the exact Start menu, taskbar, File Explorer, Windows Update, or other Windows component that led to the system-file check.

If the symptom is gone, avoid unrelated resets. If it remains, keep the SFC status, DISM status if used, CBS details when relevant, and the reproducible symptom for the next diagnostic step.

DISM RestoreHealth FAQ

Limitations

• SFC focuses on protected Windows system files. It does not repair third-party applications, ordinary personal files, device hardware, firmware, or every Windows configuration problem.
• Successful file repair does not prove that the original symptom is fixed. Retest the affected Windows component after SFC.